1. Field of the Invention
The present invention relates to an EL (Electro-Luminescence) element which is used in a for-use-on-vehicle display device, information unit display device or the like and a method of manufacturing the same.
2. Related Art
In a field of EL elements, there have hitherto been proposed various types of EL elements each of which has provided therein a color filter for the purpose of obtaining a desired luminescence color.
In this case, when the color filter is formed on the side of a glass substrate which opposes the EL element, since light leaks from between the glass substrate and the color filter, color due to light from the EL elements which does not pass through the color filter can be directly seen depending on a viewing perspective, with the result that the quality of the display becomes deteriorated.
On this account, in Japanese Patent Application Laid-Open No. 61-57497, there is disclosed an EL element wherein the color filter is formed directly on the upper electrode of the EL element. Also, an EL element that has a construction that is similar thereto is disclosed in Japanese Patent Application Laid-Open No. 1-315987 as well.
In this type of EL element, it sometimes happens that dielectric breakdown is caused due to the application of voltage. The present inventors manufactured an EL element having a color filter formed on the upper electrode thereof and observed dielectric breakdown spots in the EL element. As a result, they have found out that there is an increased probability of an occurrence of non-luminescent spots (pixel losses) each having a visible size (the diameter: 0.1 mm or so). The inventors also found that when in a dot matrix display device the dielectric breakdown spot hole size has become larger than a line width of the dot matrix display device, there occurs the phenomenon of line defects, due to the application of voltage over a long period of time. That is, the inventors have found out that when dielectric breakdown spots occur, long application of voltage brings about a propagation type breakdown mode in which the breakdown spot continues to be enlarged.